Air exhaust outsole for safety footwear

ABSTRACT

An puncture resistant outsole, for safety footwear having an upper with a vapor permeable insole wherein a top insole surface supports a foot of the wearer, the air exhaust outsole comprising: a ventilated midsole, with a top midsole surface engaging a bottom insole surface of the upper, the midsole including a ventilation channel between a side midsole surface and the top midsole surface; a puncture resistant layer with a top surface bonded to a bottom midsole surface, the puncture resistant layer comprising a puncture resistant core bonded about at least a peripheral edge in a flexible coating, the puncture resistant core being vapor impermeable comprising one of: a sheet metal plate; and multiple layers of woven fabric bonded together with a resilient rubber layer therebetween; and a tread layer with: a top surface bonded to a bottom surface of the puncture resistant layer; and a bottom tread surface.

TECHNICAL FIELD

The invention relates to an air exhaust outsole for safety footwear having a cushioning midsole with air ventilating channels to vent the interior of the upper, and a puncture resistant layer beneath the midsole, to provide an improved puncture resistant footwear with a ventilated upper.

BACKGROUND OF THE ART

The safe use of footwear in many working environments requires foot protection to avoid common injuries. Protection may include: puncture protection from sharp objects that puncture the sole of the footwear; impact and compression resistance for the toe area; metatarsal protection that reduces the chance of injury to the metatarsal bones at the top of the foot; electrically non-conductive properties which reduce hazards that may result from static electricity buildup, or reduce the possibility of ignition of explosives and volatile chemicals; and reduce the electric hazard risk of stepping on a live electrical wire.

In warehouse operations, manufacturing, heavy industry and construction, workers are required as a minimum to wear protective footwear and head protection, fall protection harnesses and other safety equipment. In general the employer provides, pays for or reimburses the workers for the costs of safety equipment. Footwear is for individual personal use and an improper fit can produce significant discomfort. Accordingly footwear is usually purchased by the worker and the costs are reimbursed by the employer. Accordingly workers exercise a high degree of personal choice over the comfort features and fashion when selecting safety footwear.

Safety shoes and boots in particular are widely used throughout workplaces to avoid easily preventable common foot injuries caused by stepping on objects that can puncture the sole of the footwear and injure the sole of the wearer's foot. Governments have established regulations for worker safety and footwear must comply with standard puncture resistance test. For example, ASTM F241305 (American Society for Testing and Materials) and the International Standards Organization ISO 20345:2011 used in Europe specifies that protective soles provide a minimum puncture resistance force in testing of 1100 Newtons (approx. 250 pounds) and CSA 2195 (Canadian Standards Association) specifies 1200 Newtons.

Modern protective footwear uses puncture resistant woven fiber layers bonded with rubber or resin. Woven fabric layers use high strength fibers, such as KEVLAR™ fibers, spun into thread and tightly woven to replace metal plates that were used in the past to protect the sole of the wearer. Resilient plastic toe caps protect the wearer's toes. In the past metal sole plates and toe caps were used, however users prefer non-metal alternatives since metal is heavy and conducts electricity, heat and cold.

Since footwear used in the workplace is often worn all day everyday, comfort is a paramount concern in addition to durability and compliance with safety requirements. Many safety footwear designs imitate the appearance and comfort of athletic shoes or dress shoes to enhance comfort as well as to comply with the wearer's fashion choices for their work clothing.

Many common designs for non-safety footwear and running shoes include ventilation of the upper to enhance wearing comfort by circulating air through the upper portion sometimes creating air movement through a pumping action as the wearer walks. Shoes for nurses for example often include superior cushioning, air bags, heel springs and ventilation for comfort due to the physical demands of that profession. Examples of ventilated footwear are described in U.S. Pat. No. 8,127,465 to Byrne et al and U.S. Pat. No. 4,078,321 to Famolare.

When wearing conventional safety footwear that include puncture protective soles, workers often experience discomfort since the protective sole prevents the escape of heat and moisture generated by the wearer's foot. The protective sole may also be made of materials that conduct cold more readily than other conventional materials of the footwear. Modern safety footwear generally uses multiple puncture resistant woven fabric layers that reduce thermal conduction as well as electrical conduction.

Safety footwear are worn outdoors in all weather and are worn all day every work day in many environments, so discomfort from heat, cold, moisture, and water penetration is a serious concern. The protective sole in safety footwear is conventionally located in the insole immediately adjacent to the wearer's sole. Discomfort arises from the use of a puncture resistant protective layer that is relatively stiff and reduces the effect of any cushioning. Puncture resistant layers are generally impermeable and impede air circulation, impede heat dissipation, and impede moisture transfer that prevents adequate drying of the insole adjacent the wearer's foot.

Accordingly, it is desirable to enhance the comfort of safety footwear while retaining the puncture protection provided by a puncture resistant layer. Comfort involves cushioning, temperature control, air circulation and moisture control, all of which are impeded by locating a stiff puncture resistant layer in close proximity to the wearer's foot.

Features that distinguish the present invention from the background art will be apparent from review of the disclosure, drawings and description of the invention presented below.

DISCLOSURE OF THE INVENTION

The invention provides an puncture resistant outsole, for safety footwear having an upper with a vapor permeable insole wherein a top insole surface supports a foot of the wearer, the air exhaust outsole comprising: a ventilated midsole, with a top midsole surface engaging a bottom insole surface of the upper, the midsole including a ventilation channel between a side midsole surface and the top midsole surface; a puncture resistant layer with a top surface bonded to a bottom midsole surface, the puncture resistant layer comprising a puncture resistant core bonded about at least a peripheral edge in a flexible coating, the puncture resistant core being vapor impermeable comprising one of: a sheet metal plate; and multiple layers of woven fabric bonded together with a resilient rubber layer therebetween; and a tread layer with: a top surface bonded to a bottom surface of the puncture resistant layer; and a bottom tread surface.

DESCRIPTION OF THE DRAWINGS

In order that the invention may be readily understood, one embodiment of the invention is illustrated by way of example in the accompanying drawings.

FIG. 1 is an exploded perspective view of a right foot safety boot where the upper is shown separated from a cushioned midsole, a puncture resistant layer and a tread layer.

FIG. 2 is a longitudinal sectional view, along line 2-2 of FIG. 3, of the air exhaust outsole including four ventilation channels extending transversely through the midsole, with a puncture resistant layer bonded to the bottom tread layer above the cushioned midsole.

FIG. 3 is a plan view of the top midsole surface of FIG. 2.

FIG. 4 is a transverse cross-sectional view along line 4-4 of FIG. 3

FIG. 5 is a transverse cross-sectional view along line 5-5 of FIG. 3.

FIG. 6 is a transverse cross-sectional view along line 6-6 of FIG. 3.

FIG. 7 is a transverse cross-sectional view along line 7-7 of FIG. 3.

FIG. 8 is a plan view of the top surface of the puncture resistant layer independent of the cushion midsole and bottom tread layer.

FIG. 9 is a transverse cross-sectional view similar to FIG. 6 showing the advantages of a puncture resistant layer positioned beneath the cushioning midsole and remote from the wearer's foot.

FIG. 10 is a transverse cross-sectional view similar to FIG. 9 showing the disadvantages of a puncture resistant layer positioned beneath the insole and close to the wearer's foot.

FIG. 11 is a transverse cross-sectional view similar to FIG. 4 showing the advantages of a puncture resistant layer positioned beneath the cushioning midsole and remote from the wearer's foot.

FIG. 12 is a transverse cross-sectional view similar to FIG. 4 showing the disadvantages of a puncture resistant layer positioned beneath the insole and close to the wearer's foot.

FIGS. 13, 14, 15, 16 and 17 are external views of a right foot example of the outsole, respectively being: a bottom view; a lateral side view; a medial side view; a front view; and a rear view.

Further details of the invention and its advantages will be apparent from the detailed description included below.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 shows an air exhaust outsole made of three layered components, namely, the air ventilating midsole 1, the puncture resistant layer 2 and the tread layer 3. The puncture resistant layer 2 is located away from the wearer's foot to enhance comfort since the midsole 1 can provide air ventilation and cushioning between the foot and puncture resistant layer 2 as described in detail below. The safety footwear includes an upper 4 with an air permeable insole 5 having a top insole surface 9 for supporting a foot of the wearer.

As seen in FIGS. 1-2, the midsole 1 has a top midsole surface engaging the bottom surface of the air permeable insole 5 of the upper 4. In the longitudinal sectional view of FIG. 2 and transverse sectional views of FIGS. 4-7 it can be seen that the midsole 1 has four transverse ventilation channels 6 that extend between outlet ports 7 in a side midsole surface and inlet ports 8 in the top midsole surface 9.

Therefore each of the four longitudinally spaced apart transverse ventilation channels 6 passes transversely through the midsole 1 and includes an inlet port 8 in the top midsole surface 9 and a pair of outlet ports 7 in opposing left and right side midsole surfaces. The inlet 8 and outlet ports 7 are in communication via internal transverse channels 6 formed within the midsole 1.

In the top view shown in FIG. 3 the inlet port 8 has a central inlet opening 10 to the ventilation channel 6. Each inlet opening 10 is joined to at least one adjacent inlet opening 10 with a shallow connecting groove 12 in the top midsole surface 9. As seen in FIG. 3, the top midsole surface 9 can also include a branching ventilating groove 13 in the ball area of the midsole 1.

The midsole 1 provides a cushion immediately adjacent to the air permeable insole 5 of the upper 4. As a result, the wearer's sole is separated from the puncture resistant layer 2 by a ventilating and cushioning midsole 1 made of a flexible compressible material, for example injection molded ethylene vinyl acetate (IMEVA), commonly known as synthetic foam rubber.

The wearer perceives substantially the same foot comfort as a ventilated and cushioned running shoe. The puncture resistant layer 2 is located immediately above a thin tread layer 3 away from the wearer's foot. The wearer does not experience the discomfort caused by conventional puncture resistant layers that are generally positioned immediately adjacent or relatively close to the insole 5 of the upper 4.

The outsole provides a cushioning and ventilated midsole 1 adjacent the insole 5 and proximal to the wearer's foot sole for enhanced comfort, air circulation, heat dissipation and moisture venting. The location of the puncture resistant layer 2 enables the footwear to provide puncture resistance while avoiding problems that arise if a puncture resistant layer 2 is located close to the wearer's sole, namely, heat retention and moisture retention within the upper 4.

To illustrate the advantages of the lower position of the puncture resistant layer 2, FIGS. 9 and 10 show a comparison between footwear according to the invention (FIG. 9) and the same footwear with a puncture resistant layer 2′ located beneath the upper 4′ (FIG. 10).

Width Increased

The puncture resistant layer 2 shown in FIG. 9 is positioned beneath the midsole 1 and above the tread layer 3. The width of the puncture resistant layer 2 is shown as dimension W. Because the puncture resistant layer 2 is immediately adjacent the tread layer 3 at the bottom of the footwear, the width W is determined by the width of the tread layer 3 and not by the width of the upper 4.

In contrast the puncture resistant layer 2′ shown in FIG. 10 is positioned beneath the upper 4′ and above the cushioning midsole 1′. The width of the puncture resistant layer 2′ is significantly narrower as shown as dimension W′ (i.e.: W′=W−x′−y′). Because the puncture resistant layer 2′ in FIG. 10 is immediately adjacent the upper 4′ beneath the wearer's foot, the width W′ is determined by the width of the upper 4.

The increase in width W results in improved foot safety for the wearer. If the wearer steps on a nail with the outer edge of the tread layer 3, and the nail is oriented at an angle towards the foot, the puncture resistant layer 2 will deflect entry of the nail point into the foam of the midsole 1. Not only will the nail be deflected, but the midsole 1 will not be damaged either.

In the example of FIG. 10, if the wearer steps on a nail, the nail is embedded into the cushion foam of the midsole 1′ before the nail point encounters the puncture resistant layer 2′. The midsole 1′ is punctured by the embedded nail causing damage. Further the nail embedded in the midsole 1′ is held in position by the surrounding midsole 1′ material exposing the wearer to possible injury if another step is taken, or at least requires the wearer to stop and remove the embedded nail.

Therefore the increased width W of the wider puncture resistant layer 2 better protects the foot of the wearer from injury and reduces puncture damage to the midsole 1.

FIGS. 9 and 10 show the heel area of the footwear like FIG. 7 along line 7-7 of FIG. 3. FIGS. 11 and 12 show a toe area of the footwear like FIG. 4 along line 4-4 of FIG. 3. In the views of FIGS. 11 and 12, the width A is greater when the puncture resistant layer 2 is positioned above the tread layer 3 compared to width A′ when the puncture resistant layer 2′ is positioned above the midsole 1′ below the upper 4′ (i.e.: A′+A−b′−c′). Accordingly, the toe area is also better protected when a wider puncture resistant layer 2 is located lower in the footwear assembly.

Improved Cushioning

The puncture resistant layer 2 in FIG. 9 is positioned away from the upper 4 and away from the wearer's foot. The midsole 1 is made of cushioning foam material and is positioned immediately below the upper 4 and the wearer's foot. The puncture resisting layer 2 does not interfere with the cushioning action of the midsole 1.

The puncture resistant layer 2′ in FIG. 10 is positioned between the upper 4′ and the midsole 1′. The puncture resisting layer 2′ is a less flexible material that interferes with the cushioning action of the midsole 1′ and exposes the sole of the wearer's foot to a hard inflexible surface.

Accordingly in the configuration shown in FIGS. 9 and 11, positioning the impermeable puncture resistant layer 2 beneath the midsole 1 provides improved cushioning between the upper 4 and the midsole 1.

Improved Venting and Cooling Air Flow

The puncture resistant layer 2 in FIG. 9 is positioned away from the upper 4 and away from the wearer's foot. The upper 4 is vapor permeable and the midsole 1 includes ventilation channels 6. As indicated with dashed arrows, air and vapor can exhaust from the upper 4 to the ventilation channels 6 which results in reduced moisture and cooling air flow within the upper 4.

In contrast the puncture resistant layer 2′ in FIG. 10 impedes the flow of air or vapor from the upper 4′ which must pass through the puncture resistant layer 2′. Puncture resistant layers 2 and 2′ are generally impermeable since they are made of woven fabric embedded in resin or rubber. A perforated puncture resistant layer 2′ would compromise the puncture resistance properties significantly.

Accordingly in the configuration shown in FIGS. 9 and 11, positioning the impermeable puncture resistant layer 2 beneath the midsole 1 better permits the passage of air and vapor from the upper 4.

Radiant Heat and Temperature Control

As noted above, the material of the puncture resistant layers 2 and 2′ absorbs heat and cold from the surfaces that the wearer walks upon. In FIGS. 9 and 11 the positioning of the puncture resistant layer 2 away from the upper 4 and the wearer's foot, impedes transfer of heat and cold to the foot. The cushioning foam of the midsole 1 acts as a thermal insulator between the foot and the puncture resistant layer 2.

As shown in FIG. 10, the puncture resistant layers 2′ being positioned immediately below the upper 4′ will absorb and retain heat from the wearer's foot, making the footwear uncomfortable in hot weather and hot environments.

Ventilation Channels

Each ventilation channel 6 joins the inlet port 8 in the top midsole surface 9 and the pair of outlet ports 7 in opposing medial and lateral side midsole surfaces. Since the midsole 1 is made of flexible foam material, the top wall 14 of the ventilation channel 6 can flex toward a bottom wall 15 under the wearer's foot pressure during walking. The top wall 14 rebounds to an initial position when foot pressure is removed, therefore the resilient action of the midsole 1 during walking alternately decreases and restores the air volume within the ventilation channel 6 to circulate air within the ventilation channel 6 and ventilate the footwear.

The midsole 1 in the heel area can also include a liquid or gas filled bag (not shown) or a compression spring (not shown) molded into the foam structure of the midsole 1. The top midsole surface 9 may also include an air/vapour permeable and liquid water resistant membrane such as GORTEX™ covering the inlet port 8 to impede entrance of liquid water into the upper 4 from the ventilation channels 6.

FIG. 8 shows a detail plan view of the top surface of the puncture resistant layer 2. The puncture resistant layer 2 is located immediately above the rubber tread layer 3 and is separated from the wearer's sole by the cushioning and ventilating midsole 1. The puncture resistant layer 2 has a top surface bonded to a bottom surface of the midsole 1 and a bottom surface of the puncture resistant layer 2 bonded to the tread layer 3 which has a textured bottom tread surface best seen in FIG. 13.

As seen in FIG. 8, the puncture resistant layer 2 has a puncture resistant core 16 bonded about at least a peripheral edge in a flexible coating 17. The flexible coating 17 in FIG. 8 is shown as a clear plastic surrounding the periphery of the puncture resistant core 16. The toe area of the coating is recessed to allow for the fitting of a protective top cap 18 (shown in FIG. 2). The flexible coating 17 allows the woven fabric puncture resistant core 16 to be bonded to the flexible foam (IMEVA) midsole 1 and also to the rubber (RB) tread layer 3. By encasing the periphery and optionally the bottom of the core 16 in a flexible coating 17, such as thermoplastic urethane (TPU), the mutual bonding of the materials is possible (IMEVA to TPU, TPU to woven fabric, and TPU to RB).

The puncture resistant core 16 can be a puncture resistant woven fabric composite or and a sheet metal plate if desired. A puncture resistant woven fabric core 16 can be assembled from multiple layers of woven fabric bonded together with a resilient layer such as rubber or other adhesive compatible with the threads of the woven fabric. Use of a metal plate as a puncture resistant core 16 in some applications is adequate, however a woven fabric puncture resistant core 16 and/or the flexible coating 17 can be selected to be resistant to electric conduction and thermal conduction. The puncture resistant woven fabric core 16 can be made of threads spun from para-aramid synthetic fiber (KEVLAR™) bonded in multiple layers of rubber as for example provided by the Italian manufacturer Lenzi Egisto S.p.a. It will be understood that the multiple layers of solid rubber bonded together with the woven fabric of the puncture resistant core 16 or a sheet metal plate, will be vapor and water impermeable.

The outsole includes a tread layer 3 best seen in FIG. 8 that may be molded of rubber (RB) and is bonded to the bottom surface of the puncture resistant layer 2. The flexible coating 17 may cover the bottom surface of the puncture resistant core 16 and can be molded to include ridges or surface features compatible with the mold pattern of the tread layer 3. In the example shown in FIG. 8, the flexible coating 17 is transparent and has ridges that match the molded windows 19 in the opaque tread layer 3, through which the transparent flexible coating 17 and puncture resistant core 16 are visible. An advantage of using a transparent flexible coating 17 is that the puncture resistant core 16 with standard markings is visible to confirm that the footwear is puncture resistant.

Although the above description relates to a specific preferred embodiment as presently contemplated by the inventors, it will be understood that the invention in its broad aspect includes mechanical and functional equivalents of the elements described herein. 

I claim:
 1. A puncture resistant outsole, for safety footwear having an upper with a vapor permeable insole wherein a top insole surface supports a foot of the wearer, the air exhaust outsole comprising: a ventilated midsole, with a top midsole surface engaging a bottom insole surface of the upper, the midsole including a ventilation channel between a side midsole surface and the top midsole surface; a puncture resistant layer with a top surface bonded to a bottom midsole surface, the puncture resistant layer comprising a puncture resistant core bonded about at least a peripheral edge in a flexible coating, the puncture resistant core being vapor impermeable comprising one of: a sheet metal plate; and multiple layers of woven fabric bonded together with a resilient rubber layer therebetween; and a tread layer with: a top surface bonded to a bottom surface of the puncture resistant layer; and a bottom tread surface.
 2. The outsole of claim 1 wherein each ventilation channel includes an inlet port in the top midsole surface and a pair of outlet ports in opposing left and right side midsole surfaces, the inlet and outlet ports being in communication via the ventilation channel formed within the midsole.
 4. The outsole of claim 2 wherein the midsole includes a plurality of longitudinally spaced apart ventilation channels.
 5. The outsole of claim 1 wherein the midsole comprises a flexible compressible cushioning material.
 6. The outsole of claim 5 wherein the flexible compressible material comprises injection molded ethylene vinyl acetate.
 7. The outsole of claim 5 wherein the ventilation channel extends between an inlet port in the top midsole surface and a pair of outlet ports in opposing left and right side midsole surfaces, wherein the ventilation channel has a top wall that flexes toward a bottom wall thereof under foot pressure and returns to an initial position when foot pressure is removed, thereby alternately decreasing and restoring an air volume within the ventilation channel to pump air through the ventilation channel.
 8. The outsole of claim 1 wherein the midsole in a heel area includes one of: a fluid filled bag; and a compression spring.
 9. The outsole of claim 2 wherein the top midsole surface includes an air permeable water resistant membrane covering the inlet port.
 10. The outsole of claim 1 wherein at least one of: the puncture resistant core; and the flexible coating, are resistant to at least one of: electric conduction; and thermal conduction.
 11. The outsole of claim 1 wherein the flexible coating covers the bottom surface of the puncture resistant layer.
 12. The outsole of claim 1 wherein the flexible coating comprises thermoplastic urethane.
 13. The outsole of claim 12 wherein the flexible coating is transparent.
 14. The outsole of claim 1 wherein the puncture resistant woven fabric comprises threads spun from para-aramid synthetic fiber.
 15. The outsole of claim 1 wherein the tread layer comprises rubber.
 16. The outsole of claim 13 wherein tread layer is opaque and includes windows through which the flexible coating and puncture resistant core are visible.
 17. The outsole of claim 1 wherein the tread layer has a thickness no greater than a thickness of the puncture resistant layer.
 18. The outsole of claim 1 wherein the puncture resistant layer has a width that is greater than a width of the bottom insole surface of the upper. 